1. Field of the Invention
The present invention relates to a sheet feeding apparatus, and more particularly, it relates to a sheet feeding apparatus such as an original feeding apparatus used with a copying machine, reader and the like, which can simultaneously rest a plurality of sheets on a predetermined processing device.
2. Related Background Art
In the past, an original feeding apparatus has been known as a typical example of such sheet feeding apparatuses, which will be now described as an example.
In the copying operation effected by an image forming system such as a copying machine and the like incorporating an original feeding apparatus, wherein originals are automatically and continuously fed to a platen, it is known that two images of two originals are printed side by side on one surface of a single recording medium (copying sheet).
FIG. 1A shows an example of the image forming system performing such copying operation.
In FIG. 1, the image forming system comprises a frame or body 100 and a platen 101 acting as an image reading portion. An original feeding apparatus 200 is disposed above the platen. The original feeding apparatus 200 comprises a stacking tray 201 on which a plurality of originals S' are stacked (original stack S), a separating portion 202 for separating the original S' from the original stack S on the stacking tray 201 one by one, feed rollers 203 for feeding the original S' separated by the separating portion 202 toward the platen 101, a sensor 204 disposed between the feed rollers 203 and the separating portion 202 and adapted to detect the original S', a whole-surface belt 205 for setting the original S' fed from the feed rollers 203 on the platen 101, an ejector roller 207 for ejecting the original S' from the platen 101 onto a sheet discharge tray or ejector tray 206.
In the above image forming system, the original stack S is set on the stacking tray with the images thereof turned upside (refer to FIG. 1A). When a copy start signal is applied to the apparatus, the separating portion 202 is rotated to separate a lower-most original S' from the original stack S and to feed it until a leading end of the original abuts against the feed rollers 203 (refer to FIG. 1B). Then, the feed rollers 203 and the whole-surface belt 205 are rotated normally so that the original S' is fed toward the platen 101; the rollers 203 and the belt 205 are stopped when a trailing end of the original S' leaves the feed rollers 203 (refer to FIG. 1C).
Then, the whole-surface belt 205 is rotated slightly reversely until the trailing end of the original S' abuts against the feed rollers 203, and then, the belt is stopped (refer to FIG. 1D). Thereafter, the separating portion 202 is rotated to separate a next or second original S' and to feed it until a leading end of the second original abuts against the feed rollers 203 (refer to FIG. 1E). Then, the feed rollers 203 and the whole-surface belt 205 are again rotated normally so that the second original S' is fed toward the platen 101; the whole-surface belt 205 is stopped when the second original S' reaches a predetermined position on the platen 101 (refer to FIG. 1F).
In this way, two originals S' are arranged side by side on the platen 101. Thereafter, when images of these originals S' are read (refer to FIG. 1G), the images of two originals S' are copied or printed on one surface of a single copying sheet. After the reading of the images has been finished, the whole-surface belt 205 and the ejector roller 207 are rotated normally to eject or discharge the originals S' on the platen 101 onto the discharge tray 206 (refer to FIG. 1H).
However, as apparent from FIG. 2 showing a nip between the feed rollers 203 in an enlarged scale, it is difficult for the leading end of the second original S' to be abutted against the trailing end of the lowermost or first original S', and thus, a clearance corresponding to a width X of the nip will be created between these ends of the two originals. Consequently, a clearance corresponding to the width X is also created between two originals S' rested on the platen 101, which leads in the drawback in the copying operation.
For example, as shown in FIG. 3, assuming that the size of the original S' is l.sub.1 and the clearance between two originals is l.sub.2, when the images of these originals are copied on a copying sheet having a size twice the original, since the first original S' is shifted by a distance l.sub.2 from an image reading area, an image portion included in a hatched area (having a width l.sub.2) of the first original S' will disappear from the copied image on the copying sheet.